Abstract:To effectively utilize tilapia skin for the preparation of collagen tripeptides with antioxidant activity，response surface methodology was adopted to optimize the enzymatic hydrolysis conditions. The quality of tilapia skin's collagen tripeptide was evaluated by comparing its molecular weight distribution，amino acid composition，and antioxidant activity with those of commercial collagen tripeptide. The results showed that the highest tripeptide content of 37.25% was obtained using a compound enzyme of alkaline protease and bromelain （enzyme dosage od 5 000 U/g at a ratio of 1∶1） under the conditions of enzymatic hydrolysis temperature of 55 ℃，liquid-solid ratio of 6.3∶1（mL/g），and pH of 9.2. Compared with commercial collagen tripeptide，the tilapia skin's collagen tripeptide had a smaller weight-average molecular weight （476 Da） and higher contents of essential amino acids （15.42%） and hydrophobic amino acids （32.53%）. Furthermore，at a concentration of 2.00 mg/mL，the DPPH and ABTS+free radical scavenging rates of tilapia skin's collagen tripeptide reached 38.55% and 61.97%，respectively，indicating superior antioxidant capacity compared to commercial collagen tripeptide.